web: extract reconnect helpers and add tests

src/web/reconnect.test.ts

@@ -0,0 +1,52 @@
+import { describe, expect, it } from "vitest";
+
+import type { WarelayConfig } from "../config/config.js";
+import {
+  computeBackoff,
+  DEFAULT_HEARTBEAT_SECONDS,
+  DEFAULT_RECONNECT_POLICY,
+  resolveHeartbeatSeconds,
+  resolveReconnectPolicy,
+  sleepWithAbort,
+} from "./reconnect.js";
+
+describe("web reconnect helpers", () => {
+  const cfg: WarelayConfig = {};
+
+  it("resolves sane reconnect defaults with clamps", () => {
+    const policy = resolveReconnectPolicy(cfg, {
+      initialMs: 100,
+      maxMs: 5,
+      factor: 20,
+      jitter: 2,
+      maxAttempts: -1,
+    });
+
+    expect(policy.initialMs).toBe(250); // clamped to minimum
+    expect(policy.maxMs).toBeGreaterThanOrEqual(policy.initialMs);
+    expect(policy.factor).toBeLessThanOrEqual(10);
+    expect(policy.jitter).toBeLessThanOrEqual(1);
+    expect(policy.maxAttempts).toBeGreaterThanOrEqual(0);
+  });
+
+  it("computes increasing backoff with jitter", () => {
+    const policy = { ...DEFAULT_RECONNECT_POLICY, jitter: 0 };
+    const first = computeBackoff(policy, 1);
+    const second = computeBackoff(policy, 2);
+    expect(first).toBe(policy.initialMs);
+    expect(second).toBeGreaterThan(first);
+    expect(second).toBeLessThanOrEqual(policy.maxMs);
+  });
+
+  it("returns heartbeat default when unset", () => {
+    expect(resolveHeartbeatSeconds(cfg)).toBe(DEFAULT_HEARTBEAT_SECONDS);
+    expect(resolveHeartbeatSeconds(cfg, 5)).toBe(5);
+  });
+
+  it("sleepWithAbort rejects on abort", async () => {
+    const controller = new AbortController();
+    const promise = sleepWithAbort(50, controller.signal);
+    controller.abort();
+    await expect(promise).rejects.toThrow("aborted");
+  });
+});